Claim Rejections - 35 USC § 103
The following is a quotation of 35 U.S.C. 103 which forms the basis for all obviousness rejections set forth in this Office action:
A patent for a claimed invention may not be obtained, notwithstanding that the claimed invention is not identically disclosed as set forth in section 102, if the differences between the claimed invention and the prior art are such that the claimed invention as a whole would have been obvious before the effective filing date of the claimed invention to a person having ordinary skill in the art to which the claimed invention pertains. Patentability shall not be negated by the manner in which the invention was made.
The factual inquiries for establishing a background for determining obviousness under 35 U.S.C. 103 are summarized as follows:
1. Determining the scope and contents of the prior art.
2. Ascertaining the differences between the prior art and the claims at issue.
3. Resolving the level of ordinary skill in the pertinent art.
4. Considering objective evidence present in the application indicating obviousness or nonobviousness.
Claims 1-19 are rejected under 35 U.S.C. 103 as being unpatentable over WO 2021/256446 A1 (= US 2023/0276701 A1) to Miyajima et al. in view of US 2021/0098714 A1 to Choi et al.
It is noted that the recitation of the temperature-dependent excitation lifetime in claim 1 is equivalent to saying that the TADF light-emitting substance has a negative ΔST. Correspondingly, Miyajima et al. discloses an OLED wherein the EML comprises a host material and a dopant which is a TADF heptazine derivative having a ΔST between -20 eV and 0.0090 eV. An example of the TADF heptazine derivative is the following compound on page 20:
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As this compound is essentially identical to the claimed light-emitting substance (see compound G3 on page 35 of the specification), it therefore must have the same temperature-dependent excitation lifetime profile. Miyajima et al. fails to teach a host material comprising a carbazole ring, an aromatic amine skeleton or a π-electron deficient heteroaromatic ring. However, Choi et al. discloses an OLED wherein the EML comprises a TADF dopant and a host material comprising a carbazole-based hole-transport compound and an azine-based electron-transport compound that together form an exciplex (pp. 1, 7, 8), and Choi et al. also discloses that the exciplex enables better energy transfer to the TADF dopant [0098]. Therefore, it would have been obvious to a person of ordinary skill in the art at the time the instant invention was filed to modify the device disclosed by Miyajima et al. by employing the host material suggested by Choi et al. so as to optimize the energy transfer efficiency from the host to the dopant and thereby improve the overall efficiency of the device.
The features of claims 2, 4 and 5 are disclosed by Choi et al. as mentioned. The features of claim 3 are disclosed by both references and they are also obvious because the T1 of the host must be at least equal to the T1 of the dopant for energy transfer to be possible. Claim 7 is obvious for the same reasons. The features of claim 6 are disclosed by Choi et al. in paragraph [0135], i.e., significant overlap between the emission (output) spectrum of the host and the absorption (input) spectrum of the dopant ensures good energy transfer from the host to the dopant (see also the figures in Choi et al.). Claims 8-10 are disclosed by Miyajima et al. as mentioned. Claims 11-19 are unpatentable for the stated reasons.
Contact Information
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/VU A NGUYEN/Primary Examiner, Art Unit 1762
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